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This paper describes how to perform contract signature in a fair way using quantum information. The protocol proposed permits two partners, users of a communication network, to perform a contract signature based on the RSA security. The authentication of the signers is based on the use of a non-local XOR function of two classical bits.
2009 Sixth International Conference on Information Technology: New Generations, 2009
We point out that the quantum digital signature scheme proposed in ICACT 2005 has three problems. According to the original description of the scheme, we find: (1) the quantum one-way function is not specified clearly; (2) the signer Alice does not use her private key in the signing process; (3) both the signing and the verification can not work well.
2016
Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols-signatures based on the Rivest-Adleman-Shamir (RSA) algorithm, the digital signature algorithm (DSA), and the elliptic curve digital signature algorithm (ECDSA)-are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally securesecure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.
In this paper, an efficient arbitrated quantum signature scheme is proposed by combining quantum cryptographic techniques and some ideas in classical cryptography. In the presented scheme, the signatory and the receiver can share a long-term secret key with the arbitrator by utilizing the key together with a random number. While in previous quantum signature schemes, the key shared between the signatory and the arbitrator or between the receiver and the arbitrator could be used only once, and thus each time when a signatory needs to sign, the signatory and the receiver have to obtain a new key shared with the arbitrator through a quantum key distribution protocol. Detailed theoretical analysis shows that the proposed scheme is efficient and provably secure.
Entropy, 2015
Signature schemes, proposed in 1976 by Diffie and Hellman, have become ubiquitous across modern communications. They allow for the exchange of messages from one sender to multiple recipients, with the guarantees that messages cannot be forged or tampered with and that messages also can be forwarded from one recipient to another without compromising their validity. Signatures are different from, but no less important than encryption, which ensures the privacy of a message. Commonly used signature protocols-signatures based on the Rivest-Adleman-Shamir (RSA) algorithm, the digital signature algorithm (DSA), and the elliptic curve digital signature algorithm (ECDSA)-are only computationally secure, similar to public key encryption methods. In fact, since these rely on the difficulty of finding discrete logarithms or factoring large primes, it is known that they will become completely insecure with the emergence of quantum computers. We may therefore see a shift towards signature protocols that will remain secure even in a post-quantum world. Ideally, such schemes would provide unconditional or information-theoretic security. In this paper, we aim to provide an accessible and comprehensive review of existing unconditionally securesecure signature schemes for signing classical messages, with a focus on unconditionally secure quantum signature schemes.
Physical Review A, 2015
Digital signatures provide guarantees on the authenticity and transferability of a message. This important cryptographic functionality is frequently used in modern communication systems. The security of currently used classical digital signature schemes, however, relies on computational assumptions, and thus they may not constitute a satisfactory long-term solution. In contrast, quantum digital signature (QDS) schemes offer information-theoretic security guaranteed by the laws of quantum mechanics. This is appealing, provided feasible schemes can be found. Here, we present two different quantum digital signature protocols which essentially use the same experimental requirements as quantum key distribution (QKD), which is already commercially available. This enables existing systems for QKD to be used also for digital signatures, which significantly extends and enhances the use of QKD systems. The first scheme is an improvement on a recent QDS scheme, removing the requirement of an optical multiport, which was a major source of losses. The second protocol is essentially a classical digital signature protocol, which employs quantum key distribution for obtaining secret shared classical keys. Relying on the security of QKD, this results in an information-theoretically secure digital signature scheme. * V. Dunjko and P. Wallden contributed equally to this work. † [email protected]
International Journal of Theoretical Physics, 2013
Very recently, an arbitrated quantum signature (AQS) scheme of classical message with an untrusted arbitrator was presented[Eur. Phys. J. D 61(3), 773 (2011)]. In this paper, the security of the AQS scheme with an untrusted arbitrator is analyzed. An AQS scheme with an untrusted arbitrator should satisfy the unforgeable property and undeniable property. In particular, the malicious verifier can not modify a message and its signature to produce a new message with a valid signature, and the dishonest signer who really has sent the message to the verifier which the verifier accepted as an authentic one cannot later deny having sent this message. However, we show that, in the AQS scheme with an untrusted arbitrator, the dishonest signer can successfully disavow his/her signature and the malicious verifier can counterfeit a valued signature for any message by known message attack when he has received a message-signature pair. Then, we suggest an improved AQS scheme of classical message with an untrusted arbitrator that can solve effectively the two problems raised above. Finally, we prove the security of the improved scheme.
2016 IEEE 6th International Conference on Advanced Computing (IACC), 2016
Quantum cryptography renders a cryptographic solution which is imperishable as it fortifies prime secrecy that is applied to quantum public key distribution. It is a prominent technology wherein two entities can communicate securely with the sights of quantum physics. In classical cryptography, bits are used to encode information where as quantum cryptography i.e. quantum computer uses photons or quantum particles and photon's polarization which is their quantized properties to encode the information. This is represented in qubits which is the unit for quantum cryptography. The transmissions are secure as it is depended on the inalienable quantum mechanics laws. The emphasis of this paper is to mark the rise of quantum cryptography, its elements, quantum key distribution protocols and quantum networks.
PLOS ONE, 2021
Quantum signature is the use of the principles of quantum computing to establish a trusted communication between two parties. In this paper, a quantum signature scheme using amplitude amplification techniques will be proposed. To secure the signature, the proposed scheme uses a partial diffusion operator and a diffusion operator to hide/unhide certain quantum states during communication. The proposed scheme consists of three phases, preparation phase, signature phase and verification phase. To confuse the eavesdropper, the quantum states representing the signature might be hidden, not hidden or encoded in Bell states. It will be shown that the proposed scheme is more secure against eavesdropping when compared with relevant quantum signature schemes.
Quantum cryptography uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random bit string known only to them, which can be used as a key to encrypt and decrypt messages. An important and unique property of quantum cryptography is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key. This results from a fundamental part of quantum mechanics: the process of measuring a quantum system in general disturbs the system. A third party trying to eavesdrop on the key must in some way measure it, thus introducing detectable anomalies. By using quantum superposition or quantum entanglement and transmitting information in quantum states, a communication system can be implemented which detects eavesdropping. If the level of eavesdropping is below a certain threshold a key can be produced which is guaranteed as secure, otherwise no secure key is possible and communication is aborted. The security of quantum cryptography relies on the foundations of quantum mechanics, in contrast to traditional public key cryptography which relies on the computational difficulty of certain mathematical functions, and cannot provide any indication of eavesdropping or guarantee of key security.
Journal of Discrete Mathematical Sciences and Cryptography, 2019
Facts say that practical cryptographic systems are now within the range. Quantum cryptography generally gives the solution which uses the various methods of polarization to leave the transmitted data undisturbed. In this work we try to improve the data security by increase the key size shared between parties involved used in quantum cryptography. Quantum cryptography uses storing the split particles involved and then measuring them and creating what they use, eliminating the problem of unsafe storage.
Physical Review A, 2011
We present a fair and optimistic [7, 8] quantum contract signing protocol between two clients that requires no communication with the third trusted party during the exchange phase. We discuss its fairness and show that it is possible to design such a protocol for which the probability of a dishonest client to cheat becomes negligible, and scales as N −1/2 , where N is the number of messages exchanged between the clients. Our protocol is not based on the exchange of signed messages: its fairness is based on the laws of quantum mechanics. Thus, it is abuse-free [9], and the clients do not have to generate new keys for each message during the Exchange phase. We discuss a real-life scenario when the measurement errors and qubit state corruption due to noisy channels occur and argue that for real, good enough measurement apparatus and transmission channels, our protocol would still be fair. Our protocol could be implemented by today's technology, as it requires in essence the same type of apparatus as the one needed for BB84 cryptographic protocol [12]. Finally, we briefly discuss two alternative versions of the protocol, one that uses only two states (based on B92 protocol [24]) and the other that uses entangled pairs (based on [20]), and show that it is possible to generalize our protocol to an arbitrary number of clients.
Entropy
We present a quantum scheme for signing contracts between two clients (Alice and Bob) using entangled states and the services of a third trusted party (Trent). The trusted party is only contacted for the initialization of the protocol, and possibly at the end, to verify clients’ honesty and deliver signed certificates. The protocol is fair, i.e., the probability that a client, say Bob, can obtain a signed copy of the contract, while Alice cannot, can be made arbitrarily small, and scales as N − 1 / 2 , where 4 N is the total number of rounds (communications between the two clients) of the protocol. Thus, the protocol is optimistic, as cheating is not successful, and the clients rarely have to contact Trent to confirm their honesty by delivering the actual signed certificates of the contract. Unlike the previous protocol (Paunković et al., Phys. Rev. A 84, 062331 (2011)), in the present proposal, a single client can obtain the signed contract alone, without the need for the other cli...
Advances in Intelligent Systems and Computing, 2019
This paper represents the overview of Quantum Cryptography. Cryptography is the art of secrecy and it is the use of quantum mechanical properties to perform cryptographic tasks. It is a way of securing the channel using quantum mechanics properties. There are so many examples of quantum cryptography but the most important example is Quantum Key Distribution, which provides a solution to the breaking of various popular public key encryption and signature schemes (e.g. RSA and ElGamal). This helps to solve the security problems and also makes the communication channel is more secure. There are so many advantages of quantum cryptography, one thing is that the quantum computer gives the quadratic speed up on the general problems and second thing is that the quantum cryptography lies in the fact it allows the completion of various cryptographic tasks. That is proven to be impossible using classical communication.
Quantum Information and Computation, 2016
Digital signatures are widely used in electronic communications to secure important tasks such as financial transactions, software updates, and legal contracts. The signature schemes that are in use today are based on public-key cryptography and derive their security from computational assumptions. However, it is possible to construct unconditionally secure signature protocols. In particular, using quantum communication, it is possible to construct signature schemes with security based on fundamental principles of quantum mechanics. Several quantum signature protocols have been proposed, but none of them has been explicitly generalised to more than three participants, and their security goals have not been formally defined. Here, we first extend the security definitions of Swanson and Stinson [1] so that they can apply also to the quantum case, and introduce a formal definition of transferability based on different verification levels. We then prove several properties that multipart...
ArXiv, 2022
Digital signatures are widely used for providing security of communications. At the same time, the security of currently deployed digital signature protocols is based on unproven computational assumptions. An efficient way to ensure an unconditional (information-theoretic) security of communication is to use quantum key distribution (QKD), whose security is based on laws of quantum mechanics. In this work, we develop an unconditionally secure signatures (USS) scheme that guarantees authenticity and transferability of arbitrary length messages in a QKD network. In the proposed setup, the QKD network consists of two subnetworks: (i) the internal network that includes the signer and with limitation on the number of malicious nodes, and (ii) the external one that has no assumptions on the number of malicious nodes. A price of the absence of the trust assumption in the external subnetwork is a necessity of the assistance from an internal subnetwork recipients for the verification of mess...
Physical Review A, 2016
Digital signatures are widely used in modern communication to guarantee authenticity and transferability of messages. The security of currently used classical schemes relies on computational assumptions. We present a quantum signature scheme that does not require trusted quantum channels. We prove that it is unconditionally secure against the most general coherent attacks, and show that it requires the transmission of significantly fewer quantum states than previous schemes. We also show that the quantum channel noise threshold for our scheme is less strict than for distilling a secure key using quantum key distribution. This shows that "direct" quantum signature schemes can be preferable to signature schemes relying on secret shared keys generated using quantum key distribution.
2015
Quantum cryptography uses quantum mechanics to guarantee secure communication. It enables two parties to produce a shared random bit string known only to them, which can be used as a key to encrypt and decrypt messages. An important and unique property of quantum cryptography is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key. The security of quantum cryptography relies on the foundations of quantum mechanics, in contrast to traditional public key cryptography which relies on the computational difficulty of certain mathematical functions, and cannot provide any indication of eavesdropping or guarantee of key security. In this paper we are discussing about various protocol introduced, possible attacks on them and prevention of those attacks.
International Journal HIT Transaction on ECCN (Electronics, Communication, Computers and Networking), pp. 27-36. Volume 1, No: 1, January 2006. , 2006
Quantum mechanics is the current best description of the world as we know it. Experiments have shown that quantum predictions are accurate up ten places of decimal. In quantum cryptography much work has been devoted to the study of Quantum Key Distribution (QKD). The purpose of QKD is to securely distribute secret keys between the users in a network. As a result, several quantum cryptographic protocols have been implemented and tested after the advent of quantum computing. In this paper, we have given a brief overview of QKD, and some practical networks that integrate QKD in the current Internet security architecture. We have also discussed some aspects of quantum network security with particular attention to Byzantine Agreement Protocol.
— This Quantum cryptography is one of the emerging topics in the field of computer industry. This paper focus on quantum cryptography and how this technology contributes value to a defense-in-depth strategy pertaining to completely secure key distribution. The scope of this paper covers the technical challenges to implement the concepts of quantum cryptography. We describe the quantum key distribution by which two users who share no secret information (without having any private or public keys known before hand) initially exchange a random quantum transmission consisting of very faint flashes of polarized light. We are focusing on practical quantum key distribution, taking into account channel losses, a realistic detection process, and imperfections in the " qubits " sent from the sender to the receiver. As we show, even quantum key distribution with perfect qubits might not be achievable over long distances when the other imperfections are taken into account.
Cryptologia, 1999
The recent application of the principles of quantum mechanics to cryptography has led to a remarkable new dimension in secret communication. As a result of these new developments, it is now possible to construct cryptographic communication systems which detect unauthorized eavesdropping should it occur, and which give a guarantee of no eavesdropping should it not occur.
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